Perhaps you should try some spelling variations:
"improving sharia performance based." » "improving sharia performances based.", "improving sharing performance based.", "improving chart performance based.", "improving shared performance based.", "improving spatial performance based.", "improving static performance based."
"improving firm performance evidence." » "improving firms performance evidence.", "improving air performance evidence.", "improving erm performance evidence."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving firm performance evidence.") or ("improving sharia performance based."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving firm performance evidence.") OR ("improving sharia performance based.")).
• Removing quotes may allow a broader search: (( improving firm performance evidence. ) or ( improving sharia performance based. )).
• Adding a wildcard symbol may retrieve word variants: (("improving firm performance evidence.") or ("improving sharia performance based."))*.